The present invention relates to a heat-resistant, paintable acrylic-based adhesive tape. More particularly, the present invention relates to a two-sided acrylic-based adhesive tape and a method of adhering both sides of the tape to two substrates, where the tape can withstand environmental conditions encountered in automotive, appliance, and other commercial paint processes without degradation or a reduction in adhesive properties of the tape.
Acrylic pressure sensitive adhesive tapes are widely used in the automotive and appliance industry to bond a wide variety of substrate materials, and in particular, the application of painted exterior automotive body side moldings, sub-assemblies or trim parts. A common method of application is to use an acrylic attachment tape comprised of a foam core which adheres the substrate materials to the vehicle or appliance. However, a disadvantage of such foam core tapes is that they cannot withstand exposure to a paint bake cycle in which the part is painted and subsequently exposed to high temperatures in a paint oven to cure the painted part. For example, the foam core loses compressibility after the introduction of paint, thereby reducing the ability of the tape to sufficiently wet-out to the mating surface. In addition, the foam core may also break down as entrapped air in the foam expands at the elevated temperatures encountered in the bake cycle, rupturing the foam's cell structure, which also impedes wet-out and structural strength. Expanded gas can also collect at the tape-surface interface where it interferes with surface wet-out and bond strength.
In order to avoid the degradation of foam core acrylic tapes, the use of a separate masking tape has been employed which is applied to the part prior to the paint bake cycle in the area of the part which is to receive the foam core acrylic attachment tape to prevent that area from receiving paint. The masking tape is then removed after the paint bake cycle and the attachment tape is applied. However, the use of the masking tape adds additional steps and materials to the manufacturing process, which is both time-consuming and costly.
In order to avoid this extra step, the use of adhesive tapes which are heat-resistant have been developed. These adhesive tapes generally comprise a two-sided solid acrylic-based carrier and a heat resistant liner on one side of the carrier. The tape can be attached on one side to a substrate such as an automotive part and then exposed to elevated temperatures such as a paint baking process without being subject to degradation. The liner may be removed at a later time such that the part can be adhered to a second substrate surface, such as the exterior surface of an automobile, which is then subjected to a paint baking process in a separate step.
However, in order to save additional steps, it would be desirable to be able to apply a two-sided adhesive tape to two substrates prior to the paint baking process so that the substrates could be painted simultaneously. Accordingly, there is still a need in the art for a tape which may be applied to two substrates and which is not adversely affected when exposed to paint, primers, and elevated temperatures such as those encountered in automotive, appliance, and other commercial painting processes.